Yaroslav the Wise Novgorod State University has developed an unusual four-shaft two-stroke internal combustion engine with 4 crankshafts. They are placed vertically at the corners of a conditional square.

Between them are 4 composite cylinders with oppositely moving pistons. This design allows for a more compact structure and high specific power.

The developers placed separate combustion chambers between the cylinder halves. In cross-section, their shape is a projection of a hyperboloid onto a plane.

The spherical piston crowns and the special shape of the chamber are intended to create intense swirling of the fuel-air mixture. According to the authors, the vortex will persist until ignition and accelerate the combustion process. Several spark plugs can also be installed in the chamber.

For the calculated engine variant, engineers chose a working volume of 1.207 liters. At a rotational speed of 5,000 rpm and an average effective pressure of 0.6 MPa, the power unit can produce 60.4 kW, or about 82 hp.

From the editors of "Pervy Tekhnichesky": the attempt to pack four crankshafts and opposed pistons into a "square" provides excellent mass balance and beautiful vortex aerodynamics.

However, the cumbersome shaft synchronization system, the inevitable overheating of the combustion chamber cramped in the center, and the modest 82 hp make the design economically unfeasible compared to classic internal combustion engines.